A support matrix of this type is known from German Offenlegungsschrift No. 23 02 746.
In this known support matrix, the individual layers of steel panels can be welded together. The support matrix itself can be retained in a jacket by holding means, preferably disposed in front of the end of the matrix, this holding means consisting for example of intersecting struts, wires, or rods, or a wire mesh.
Welding the individual layers of steel paneling is a costly procedure. The holding means at the ends of the matrix do not always suffice to prevent a mutual axial displacement of the individual layers of the steel panels in the matrix.